$$\lim_{x \to 0^-} \left(4 x + 1\right)^{\frac{1}{x}} = e^{4}$$ More at x→0 from the left $$\lim_{x \to 0^+} \left(4 x + 1\right)^{\frac{1}{x}} = e^{4}$$ $$\lim_{x \to \infty} \left(4 x + 1\right)^{\frac{1}{x}} = 1$$ More at x→oo $$\lim_{x \to 1^-} \left(4 x + 1\right)^{\frac{1}{x}} = 5$$ More at x→1 from the left $$\lim_{x \to 1^+} \left(4 x + 1\right)^{\frac{1}{x}} = 5$$ More at x→1 from the right $$\lim_{x \to -\infty} \left(4 x + 1\right)^{\frac{1}{x}} = 1$$ More at x→-oo